Chapter 17 BIO333

Treadmiling (In actin filaments)

+ end of actin monomers are continuously added on while the - ends are falling of. (Unique to actin only happens within actin)

2 motor proteins within the microtubules

- Kimesin (Moves towards the +) - Dynein (Moves towards the -)

dynamic instability

A property of actin filaments in the cytoskeleton, characterized by rapid shortening or lengthening of individual filaments.

Intermediate structure (middle)

Alpha helix(1) and coiled like dimer(2)

intermediate filaments

Cable like structure: Provides for anchorage

Desmosomes (anchoring junctions)

Connect to plasma membrane gives cell strength

Actin filament (smallest)

Cortex helps maintain the cells shape

Cilia and flagella are stable therefore they do not undergo

Dynamic instability

Researchers tried to explain how vesicular transport occurs in cells by attempting to assemble the transport components. They set up microtubular tracks along which vesicles could be transported, and they added vesicles and ATP (because they knew the transport process requires energy). Yet, when they put everything together, there was no movement or transport of vesicles. What were they missing?

Motor proteins

2. Which of the following statements about the cytoskeleton is true?

Movement of cilia and flagella is the result of motor proteins causing microtubules to move relative to each other.

Lamins

The type of intermediate filament found inside the nucleus.

Cells require which of the following to form cilia or flagella?

Tubulin

Motor proteins help

Vesicle movement along the axon

Spherocytosis is a human blood disorder associated with a defective cytoskeletal protein in the red blood cells (RBCs). What do you suspect is the consequence of such a defect?

abnormally shaped RBCs

Actin filaments grow from the + end (This is usually more stable) but could

also grow from the - end.

ATP hydroylsis drives

dynamic instability.

microtubules polarized ends

grows from the positive end. (beta end)

Amoebae move by crawling over a surface (cell crawling), which involves _____.

growth of actin filaments to form bulges in the plasma membrane

microtubules structure

hollow tubes; wall consists of 13 columns of tubulin molecules

The coiled-coil dimers are

keratin filaments (epithelial cells)

Actin binding proteins act to

regulate assembly and function.

Actin filament structure

rope like structure: made of actin monomers to form filaments.

Myosin

thick filament

Microtubules (largest)

transportation cellular divison

Tublin bound GDP is more stable than

tublin bound GTP

Actin monomers have ATP binding sites

which hydrolyze ADP